Investigation of 70 MeV iron irradiation induced defects in C-silicon

Single crystal p-type silicon wafers of 0.05 Omegacm resistivity and orientation were irradiated with 70 MeV Fe-56 ions at fluence levels varying from 5 x 10(12) to 5 x 10(14) ions cm(-2). The high-resolution X-ray diffraction (XRD) and electron spin resonance (ESR) measurements were carried out to investigate the defect levels. From XRD studies it is found that the radiation induced defect density increases with increasing fluence up to 5 x 10(13) ions cm(-2) and thereafter it saturates. The screw dislocation density was found to change from 1.59 x 10(6) to 1.93 x 10(8) cm(-2) with increasing ion fluence. The strain induced in irradiated samples varied from 5.2 x 10(-4) to 9 x 10(-5) Nm(-2) with increasing ion fluence. ESR study indicates the presence of different types of defect centers. The dominant signal obtained at g value 2.0063 is attributed to the dangling bond states of silicon. (C) 200